Finding Your Flange Size

Just like with breastfeeding, pumping your breasts should not be painful or uncomfortable. While some discomfort and pain may happen, the occurrence of either could be an indicator that something needs to change. Sometimes soreness, pinching, irritation, and clogged milk ducts could be a result of simply not having the correct flange size.

What is a flange?

A breast pump flange (or breast shield) is a cone-shaped plastic or silicone cup that fits directly over your nipple to form a seal around the areola. This seal is necessary for the pump to create a vacuum that gently draws the nipple into the flange tunnel for milk extraction.

Why does flange size matter?

Not having the correct flange size could impact your milk flow and make pumping uncomfortable. By finding the correct size you can comfortably maximize milk production. Learn more about the impact of flange size on our blog. 

How do I find out my flange size?

To determine your flange size you will need to measure your nipple. Use a nipple ruler or other measuring tool to find the diameter of your nipple (the horizontal width across it) in millimeters (1 cm = 10mm). Measure the nipple alone and do not include the areola, which is the area just outside your nipple. Add 0-3 mm to this measurement to find your flange size. The correct flange size should allow only the nipple to enter the flange tunnel, be comfortable, and result in your breasts feeling well-drained after a pumping session.

Make sure to measure both nipples. You may need two different sizes!  

Quick Tip

No ruler? You can use these common household items to measure: AAA Battery = 11mm, AA Battery = 15mm, Dime = 18mm, Penny = 20mm, Nickel = 22mm, and a Quarter is 24mm.

How can I tell if my flange size is wrong? 

If your flange size is incorrect, you may experience:

• Pain with breast pumping
• Lower breast milk production
• A pinching, pulling, or squeezing sensation at the nipple
• A discolored nipple or areola
• Excessive nipple swelling
• Leaking milk on the underside of the flange

Please Note: It is ok for the nipple to touch the sides of the tunnel as long as it is not painful.

                                          Too Small                                                          Too Large

Where can I get other size flanges? 

Motif offers multiple breast shield sizes for each of our breast pumps that can be purchased on our website. Find out more here. 

I can't find my exact flange size, what do I do?  

Silicone inserts are available in a wide range of sizes and are compatible with most breast pump flanges.